A solid-state, two-dimensional image sensing device having a matrix of pixels each of which employs a photosensor that generates a photocurrent and a MOS circuit which outputs a signal proportional to the logarithm of the integral over time of the photocurrent. The sensor includes an integration control switching device so that all pixels in the array have equal integration time. The sensor integrates the signal for each pixel for a period of time and stores the integrated signal in a pixel signal storage location. To read out the stored signal each pixel includes an amplifier to increase the signal during read out. The sensor further accumulates signal in either a MOS transistor pn-junction or a secondary pixel storage location during a time that the integrated pixel signal is being read out so that image information can be collected continuously even while the integrated pixel signal for each pixel is being read.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An image pickup device having a plurality of pixels, each of said pixels comprising: a photoelectric converting device; an integrating circuit for integrating an output signal from said photoelectric converting device to generate a voltage; an amplifier for amplifying said voltage from said integrating circuit; and a lead-out path for leading out said amplified voltage onto an output signal line, wherein said amplifier includes an amplifier transistor having a first electrode, a second electrode, and a control electrode, said integrating circuit being connected to said control electrode, said second electrode being connected to said output signal line, and wherein said photoelectric converting device includes a photodiode which generates a photocurrent proportional to incident light and a logarithmic converter which generates said output signal based on said photocurrent, said output signal being a voltage proportional to the logarithm of said photocurrent.
2. An image pickup device in accordance with claim 1 , wherein said image pickup device includes a plurality of output signal lines and at least a portion of said plurality of pixels are connected to each of said output signal lines, each output signal line having a load resistor connected between said output signal line and a voltage source line.
3. An image pickup device in accordance with claim 2 , wherein said load resistor is a resistor transistor having a first electrode connected to a respective one of said output signal lines, a second electrode for connection to a first direct-current voltage via said voltage source line, and a control electrode for connection to a direct-current voltage.
4. The image pickup device according to claim 3 , wherein said amplifier transistor is an n-channel MOS transistor having a first electrode for connection to a second direct-current voltage, said second direct-current voltage being lower in potential than said first direct-current voltage.
5. The image pickup device according to claim 3 , wherein said amplifier transistor is a p-channel MOS transistor having a first electrode for connection to a second direct-current voltage, said second direct-current voltage being higher in potential than said first direct-current voltage.
6. An image pickup device in accordance with claim 1 , further comprising a first switching device connected between said photoelectric converting device and said integrating circuit for selectably communicating said output signal to said integrating circuit.
7. An image pickup device in accordance with claim 6 , further comprising an integrating circuit resetting device for selectably resetting a voltage in said integrating circuit.
8. An image pickup device in accordance with claim 7 , further comprising a second switching device connected between said amplifier and said output signal line for selectably communicating said amplified voltage out onto said output signal line.
9. An image pickup device in accordance with claim 8 , wherein said logarithmic converter comprises first and second MOS transistors each of which includes first and second electrodes and a control electrode, said photodiode being connected to said first electrode and to said control electrode of said first MOS transistor, said control electrode of said first MOS transistor being connected to said control electrode of said second MOS transistor, said integrating circuit being connected to said second electrode of said second MOS transistor.
10. An image pickup device in accordance with claim 9 , wherein each of said amplifier transistor, said first and second MOS transistors, said first switching device and said second switching device are n-channel MOS transistors.
11. An image pickup device in accordance with claim 9 , wherein each of said amplifier transistor, said first and second MOS transistors, said first switching device and said second switching device are p-channel MOS transistors.
12. An image pickup device having a plurality of pixels, each of said pixels comprising: a photoelectric converting device; an integrating circuit for integrating an output signal from said photoelectric converting device to generate a voltage; an amplifier for amplifying said voltage from said integrating circuit; and a lead-out path for leading out said amplified voltage onto an output signal line, wherein said integrating circuit includes: a first capacitor having one terminal connected to said photoelectric converting device; a second capacitor having one terminal of said second capacitor being connected to said amplifier; a capacitor switching device disposed between said first capacitor and said second capacitor for switchably coupling one terminal of said first capacitor with said one terminal of said second capacitor so that both of said first and second capacitors can integrate said output signal from said photoelectric converting device when said capacitor switching device is in a closed position and only said first capacitor can integrate said output signal from said photoelectric converting device when said capacitor switching device is in an open position, said one terminal of said second capacitor being connected to said amplifier even when said capacitor switching device is in an open position.
13. An image pickup device in accordance with claim 12 , further comprising an integrating circuit resetting device for selectably resetting a voltage in said integrating circuit.
14. An image pickup device in accordance with claim 1 , wherein said integrating circuit includes: a transistor having a first electrode, a second electrode, and a control electrode, said control electrode being connected to said logarithmic converter to receive said converted voltage; and a capacitor having one terminal connected to said second electrode of said transistor to generate a second voltage based on an output of said transistor.
15. An image pickup device in accordance with claim 14 , wherein said integrating circuit further comprises a switch connected between said transistor and said capacitor for selectably communicating an output from said transistor to said capacitor so that accumulation of said second voltage in said capacitor may be controlled thereby.
16. An image pickup device in accordance with claim 15 , wherein said transistor has a pn junction capacitance and is adapted to accumulate a charge based on an output of said logarithmic converter when said switch is in an open position.
17. An image pickup device in accordance with claim 1 , wherein said integrating circuit includes: a first transistor having a first electrode, a second electrode, and a control electrode, said control electrode begin connected to said logarithmic converter to receive said converted voltage; a first capacitor, one terminal of said first capacitor being connected to said second electrode of said first transistor to receive an output from said first transistor, a second capacitor, one terminal of said second capacitor being connected to said second electrode of said first transistor via a switch so that said first capacitor generates a second voltage based on an output of said transistor when said switch is in an open position and said first capacitor and said second capacitor together generate said second voltage when said switch is in a closed position.
18. An image pickup device in accordance with claim 3 , wherein a number of said load resistors is smaller than a number of said plurality of pixels.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
April 1, 1999
May 11, 2004
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